avb_messages.h

/*
 * Copyright 2016 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#ifndef AVB_MESSAGES_H_
#define AVB_MESSAGES_H_

extern "C" {

#include <err.h>
#include <stdint.h>

}  // extern C

// Message serialization objects for communicating with Android
// Verified Boot app.
namespace avb {

// error codes for AVB protocol
enum class AvbError : uint32_t {
  kNone = 0,      // All OK
  kInvalid = 1,   // Invalid input, e.g. slot error is not valid.
  kInternal = 2,  // Error occurred during an operation in Trusty
};

// Abstract base class of all message objects. Delegates specialized
// serialization to pure virtual functions implemented by subclasses.
class AvbMessage {
 public:
  // Returns serialized size in bytes of the current state of the
  // object.
  virtual uint32_t GetSerializedSize() const = 0;

  // Converts the object into its serialized representation. Returns
  // number of bytes serialized. |payload| points to the start of
  // the the message buffer, |end| points past the end of the message
  // buffer.
  virtual uint32_t Serialize(uint8_t* payload, const uint8_t* end) const = 0;

  // Inflates the object from its serial representation. |payload| points to
  // start of the message buffer, |end| points past the end of the message
  // buffer. Returns a Trusty error.
  virtual int Deserialize(const uint8_t* payload, const uint8_t* end) = 0;

  void set_error(AvbError error) { error_ = error; }
  AvbError get_error() const { return error_; }

 private:
  AvbError error_ = AvbError::kNone;
};

class RollbackIndexRequest : public AvbMessage {
 public:
  RollbackIndexRequest() {}
  RollbackIndexRequest(uint32_t slot, uint64_t value)
      : value_(value), slot_(slot) {}

  uint32_t GetSerializedSize() const override;
  uint32_t Serialize(uint8_t* payload, const uint8_t* end) const override;
  int Deserialize(const uint8_t* payload, const uint8_t* end) override;

  void set_slot(uint32_t slot) { slot_ = slot; }
  void set_value(uint64_t value) { value_ = value; }
  uint64_t get_value() const { return value_; }
  uint32_t get_slot() const { return slot_; }

 private:
  uint64_t value_ = 0;  // Value to write to rollback index.
  uint32_t slot_ = 0;   // Slot number of requested rollback index.
};

class RollbackIndexResponse : public AvbMessage {
 public:
  RollbackIndexResponse() {}
  RollbackIndexResponse(uint64_t value) : value_(value) {}

  uint32_t GetSerializedSize() const override;
  uint32_t Serialize(uint8_t* payload, const uint8_t* end) const override;
  int Deserialize(const uint8_t* payload, const uint8_t* end) override;

  void set_value(uint64_t value) { value_ = value; }
  uint64_t get_value() { return value_; }

 private:
  uint64_t value_ = 0;  // Value of requested rollback index.
};

class GetVersionRequest : public AvbMessage {
 public:
  GetVersionRequest() {}

  uint32_t GetSerializedSize() const override { return 0; }
  uint32_t Serialize(uint8_t* payload, const uint8_t* end) const override {
    return 0;
  }
  int Deserialize(const uint8_t* payload, const uint8_t* end) override {
    return NO_ERROR;
  }
};

class GetVersionResponse : public AvbMessage {
 public:
  GetVersionResponse() {}
  GetVersionResponse(uint32_t version) : version_(version) {}

  uint32_t GetSerializedSize() const override;
  uint32_t Serialize(uint8_t* payload, const uint8_t* end) const override;
  int Deserialize(const uint8_t* payload, const uint8_t* end) override;

  void set_version(uint32_t version) { version_ = version; }
  uint32_t get_version() { return version_; }

 private:
  uint32_t version_ = 0;
};

}  // namespace avb

#endif  // AVB_MESSAGES_H_